The invention relates to method for synthesizing metal/metalloid oxide particles with rare earth metals, especially metal/metalloid oxides with fluorescent properties. In addition, the invention relates to submicron metal/metalloid oxide particles with rare earth metals and displays produced from these particles.
Electronic displays often use phosphor materials, which emit visible light in response to interaction with electrons. Phosphor materials can be applied to substrates to produce cathode ray tubes, flat panel displays and the like. Improvements in display devices place stringent demands on the phosphor materials, for example, due to decreases in electron velocity and increases in display resolution. Electron velocity is reduced in order to reduce power demands. In particular, flat panel displays generally require phosphors that are responsive to low velocity electrons or low voltages.
In addition, a desire for color display requires the use of materials or combinations of materials that emit light at different wavelengths at positions in the display that can be selectively excited. A variety of materials have been used as phosphors. In order to obtain materials that emit at desired wavelengths of light, activators have been doped into phosphor material. Alternatively, multiple phosphors can be mixed to obtain the desired emission. Furthermore, the phosphor materials must show sufficient luminescence.
In addition, technological advances have increased the demand for improved material processing with strict tolerances on processing parameters. As miniaturization continues even further, material parameters will need to fall within stricter tolerances. Current integrated circuit technology already requires tolerances on processing dimensions on a submicron scale.
Various metal compositions exhibit desired phosphorescent properties upon excitation. Specifically, various metal oxides, including rare earth metal oxides exhibit fluorescence. In addition, doping of rare earth metals into non-rare earth metal oxides can be used to adjust the wavelength and luminosity of the phosphor particles.
In a first aspect, the invention pertains to a method for producing metal/metalloid oxide particles comprising rare earth metals. The method includes reacting a reactant stream in a gas flow wherein the reaction is driven by energy from a light beam. The reactant stream comprises a rare earth metal precursor and an oxygen source. The metal oxides can also include a non-rare earth metal/metalloid by introducing a non-rare earth metal/metalloid precursor into the flow.
In a further aspect, the invention pertains to a collection of particles comprising a metal/metalloid oxide having an average particle size from about 15 nm to about 1 micron. The metal/metalloid oxide comprises a non-rare earth metal oxide wherein less than about 10 mole percent of a stoichiometric amount of a non-rare earth metal/metalloid is substituted with rare earth metal. The metal/metalloid oxide particles can be used in a display device.
In another aspect the invention pertains to a collection of particles comprising barium magnesium aluminum oxide having an average particle size of less than 500 nm.
Furthermore, the invention pertains to a method of making a collection of metal/metalloid sulfides particles with an average particle size of less than about 500 nm. The method comprises contacting metal/metalloid oxide particles with H2S at a temperature below the melting temperature of the metal/metalloid oxide particles and the metal/metalloid sulfide particles. The metal/metalloid oxide particle have an average particle size under 500 nm.
In addition, the invention pertains to a collection of rare earth doped metal/metalloid sulfide particles having an average particle size from about 15 nm to about 500 nm.